Alkylation of isoparaffins



. Patented Jan. 9, 1945 UNITED STATES PATENT OFFlCE smm'rron orr'soruasrrms Carl B. Linn and Vladimir N. Ipatiefl, Riverside, Iii.,assignors to Universal Oil Products Company, Chicago. llli, acorporation of Delaware No Drawing. Application December as, 1942,

- Serial No. 410,2 3

.19 Claims. (Cl. 260683.4)

vThe present invention relates to the synthesis of hydrocarbons by theinteraction of saturated hydrocarbons, particularly isoparaiilnichydrocarbons,.with oleflnic hydrocarbons. in the presence of a novel.alkylation catalyst. It-is more particularly concerned with theproduction of substantially saturated gasoline boiling range bydrocarbons having high antiknock values by the alkylation' of,isoparaflins with normally gaseous mono-oleflns.

Numerous catalysts have been proposed for the alkylation ofisoparaflinichydrocarbons with oleflnic hydrocarbons including such liquid catalystsas sulfuric acid, phosphoric acid, fluorosulfonic acid, chlorosulfonicacid, hydrogen fluoride, etc. However, these catalysts are not capableof efparaiflns and ethylene. Although some of the spirit art catalystsare useful when propylene is employed as the oleflnic reactant,"nevertheless certain disadvantages are often inherent such as Q rapiddeterioration of the catalyst in the case of sulfuric acid.

In one specific embodiment the present invention comprises a'process forthe alkylation of isoparaflins with ethylene in the presence of a vfecting satisfactorily the reaction between isoylbutane as well assmaller amounts of other hexanes such as 2.2-dimethylbutane orneohexane. However, the higher homologs of isobutane, such asisopentane, isohexane, etc. are' equally useful in the production ofhigher molecular weight isoparafllns according to the present invention.Although the catalysts of the present invention are particularlyapplicable when ethylene is employed as the alkylating agent, ourinvention is broader in'scope and the catalyst may be used generally forreacting saturated hydrocarbons including naphthenes and isoparai--flnic or other branched chain hydrocarbons containing at least onetertiary carbon atom with either normally gaseous or normally liquidoleflnic hydrocarbons, particularly mono-oleflns containing from 2 toabout 12 carbon atoms per molecule. The term isopara'ilin" as usedthroughout this specification is intended to include all alkylatableparafllnic hydrocarbons.

Oleflnic hydrocarbons which may be employed as alkylating agents withinthe broad scope of the present invention may be either normally catalystconsisting essentially of boron trliiuoride and an acid fluoride,particularly an alkali metal acid fluoride. I 1

Whereas alkylation catalysts such as sulfuric acid or hydrogen fluorideare useful in the alkylation of isobutane with the highermolecularweight and more reactive mono-oleflns, such as amylenes, butylenes, andto a certain extent,

7 propylene, these catalysts are not practical in the alkylation' ofisobutane with ethylene? Bulfuric acid is particularlyunsuitable sinceeven under severe operating conditions mostof the ethylene reactsto form,ethyl sulfuric acid orv diethyl sulfate. However, we have found that acomposite of boron trifluoride and an acid fluoride such as sodium orpotassium acid fluoride willreadily effect alkylation of isoparamns withethylene. l M

The alkylation of isoparaiilns, particularly butane, with oleflnichydrocarbons is an important step in the production of saturated motorfuels which are useful for aviation purpdses'. Isobutane is readilyavailable from cracking plant gases, natural gases, and from varioushydrocarbon conversion-processes. Ethylene 'is' also produced inrelatively large quantities in cracking and other hydrocarbon conversionoperations. Isobutane and ethylene may be racted to form valuablehexanes, particularly 2,3-dimethfluoride catalyst may be carried out ata temgaseous or normally liquid as hereinbefore described, andin'certain instances polymers of the lower boiling oleflns may also beemployed .although not necessarily under the. same operating conditions.For example, when oleflnic polymers are reacted with isoparamns itisgenerally desirable toemploy a somewhat higher molal ratio ofisoparaflin to olefin in the hydrocarbon charging stock than wouldordinarily be used when monomeric oleflnic reactants are employed. It isalso possible to employ mixtures of normally gaseous and normally liquidreactants or hydrocarbon fractions which contain appreciable amounts ofnormal parafllns or naphthenes.

Boron triiluoride alone is not an alkylation ca'talyst,'but if hydrogenfluoride is present in addition to the boron triiluoride, satisfactoryalkylation may be obtained. In certain cases water and boron trifluorldewill catalyze the alkylation of isoparaillns with oleflns although notnecessarily under the same operating conditions or with the same resultsas are obtained when boron trlfiuoride and hydrogen fluoride are chargedto the process. The acid fluorides alone are also inactive as alkylatingcatalysts.

The alkylation of naphthenic or isoparamnic hydrocarbons with oleflnichydrocarbons in the presence of the boron trifluoride-alkali metal acidperature offrom about0 C. to "about 100' C.

' although a more preferable operating range is 65 from about .10" C. toabout C. it is highly desirable that the reaction be carried out undersuflicient pressure to maintain a substantial portion of the reactantsin the liquid phase, for exam from about 10 to about 200 atmospheresdependent upon the amount of boron trifluorlde present, the temperatureof the reaction, and

o her factors. In order to minimize poly- .....iz 'n ofgth'e oleflnicreactants-the hydrocanv n feed to' the alkylation reaction zone shouldcontain a substantial excess of saturated hydrocarbon reactants overoleflnic hydrocarbons, for

' example, a molal ratio of isoparafllns to oleflnsof,

from. about 3:1 to about 15:1 or higher. If desired. olefinic reactantsmaybe introduced at spaced points throughout the alkylation zone inorder to-maintain the desired high isoparaflln to olefin ratio.

' um. 'ihe acid fluorides are sometimes referred to as hydrofluoridesand are oftenrepresented by formulae such as the following: KEHF,KF.2HF,

and KRSHF. In general the mono hydrofluorides are more stable and aretherefore preferred, but under proper operating conditions, the d-iandtrihyd'rofluorides may also be used; The stability of the mono acidfluorides or hydrofluorides of the alkali metals decreases in thefollowing order:

sodium, potassium, rubidium and caesium. It is,

wiore preferred that the acid fluorides of alkylation method of thepresent invenia y" be conducted in a batch operation or referably in acontinuous operation. The

empicying' a catalyst chamber containing solid granule-s or'preformedpills of the solid acid I The isoparafflnic and oleflnic reactants ithboron trifluoride are then passed the catalyst chamberatalkylating coniof pressure, temperature; and reaction riroca-rbon reaction products andrecycled lkylation zone for reuse. The boron trimay be introduced to thealkylatlon 1? chamber separately from the. hydrocarbon re- *actants, or,more conveniently, it may be introduced in solution in the isobutane.The flxed bed -of'pc ;assium"r sodium acid fluoride may be maintained inone or a plurality of reaction zones as desired. ,The acid fluoridegranules-may be present alone or the acid fluoride may be supported-v onor composited with a suitable carrying medium or other substantiallyinert fllleror binder for the granules-or pllled particles. In anothermethod of operation, the alkylation zone ma comprisea mechanicallyagitated zone in which finely divided potassium acid fluoride ishesitated in the form of slurry with the hydrocarbon reactants and borontrifluoride. It will usually be necessary to incorporate a cooling zoneer other heat exchange means in the alkylation The.

s and potassium be used. It will be ap- Boron trifluoride may beseparated from 55 zone, or between stagesif a multiple zone system isemployed. in order to control the exothermic alkylation reaction.

In the case ofthe preferred operation wherein 5 potassium or sodium acidfluoride is maintained as a flxed bed, the ellluent material from thealkylation zone is introduced into. a. separation step whereinhydrocarbon reaction products are separated from boron trifiuoride whichcan then be recycled to the alkylation stage as hereinbefore described.The hydrocarbon reaction'products are fractionated to separate desiredalkylation products from unconverted isoparamns. The latter are recycledto the alkylation zone in order ratio in the hydrocarbon feedstock.Light hydrocarbon contaminants in the charging stock to th process mayalso ,be removed in the fractlonation step in order to prevent theiraccumulatlon in, the alkylation system. For example, if

appreciable amounts of ethane, propane, or normal butane are introducedwith the fresh hydrocarbon feed it will be desirable to remove theseconstituents during the fractionation operation.

In general it is not intended to limit the broad scope of the presentinvention to any particular method of contacting the catalyst and there- The following speciflc example is introduced in order to illustratethe nature of the present invention as it is applied to the alkylationof iso- (KEHF) was charged into a mechanically agithroughout the courseof the run from a weighed duraluminum cylinder in sufllcient quantitiesto maintain an average pressure of 275 pounds'per 'square inch gauge. Atthe end of the run the contents of the reaction vessel were dischargedinto another vessel and pressure was then released through a traincontaining an alkali scrubber, a calcium chloride drying tower, andreceivers cooled to 80 C. After the unreacted ethylene, and isobutanewere thus released the remaining liquid product was distilled.

The liquid product comprising C5 and heavier hydrocarbons weighed 240grams and there was also obtained 110 grams of condensable gas havingthe following analysis:

Mol per cent Ethylene 4.9

Ethane 0.5

Propylene 1.6

Propane 10.6

Butanes 74.7

Cs+ u The ASTM octane number of the liquid product to maintain thedesired high lsoparaifln to olefin 3. A process for the production ofsubstantially saturated motor fuel which comprises reacting anisoparaflln with an olefln under alkylating conditions in the presenceof boron trifluoride and an acid fluoride.

4. The process or claim 1 wherein said acid fluoride comprises an acidfluoride of an alkalimetal. I

5. A process for the synthesis of hydrocarbons which comprisesalkylating an isoparaflln with an olefin in the presence of a, catalystconsisting essentially of boron trifluoride and an alkali metal acidfluoride at a temperature of from about C. to about 50 C.

6. A process for the synthesis of hydrocarbons which comprises reactingan isoparaflinic hydrocarbon with an oleflnic hydrocarbon underalkylating conditions in the presence of a catalyst consistingessentially of boron trifluoride and potassium acid fluoride.

7. A process for the synthesis of hydrocarbons which comprises reactingan isoparafllnic hydrocarbon' with an oleflnic hydrocarbon underalkylating conditions in the presence of a catalystconsistingessentially of boron trifiuoride and so- 8. A process for the synthesisof hydrocarbons which comprises alkylating isobutane'with ethylene inthe presence of a catalyst consisting-essentially of boron trifiuorideand an alkali metal acid 11. A process for the production or hexaneswhich comprises reacting isobutane with ethylene at a temperature offrom about 10 C. to

about 50' C. under apressure sumcient to maintain a substantial portionof the reactants in the liquid phase in the presence or an alkylatingcatalyst consisting essentially oi boron trifluoride and an alkali metalacid fluoride.

12. A process for the production of 2,3-dimethylbutane which comprisesalkylating isobutane with ethylene in the presence of a catalystconsisting essentially or boron trifluoride and an alkali metal acidfluoride at a temperature or from about 10 C. to about 50 C. under apressure suflicient to maintain a substantialportion or the reactants inthe liquid phase and while maintaining a substantial molar excess ofisoparaflin over olefln in the hydrocarbon feed to the alkylation zone.

13. A process for the production or 2,3-dimethylbutane which comprisesalkylating isobutane with ethylene in the presence of a catalystconsisting essentially of boron trifluoride and potassium acid fluoride.

14. A process for the production or 2,3-dimethylbutane which comprisesalkylating isobutane with ethylene in the presence of a catalystconsisting essentially o1 boron trifluoride and sodium acid fluoride.

15. A process tor the synthesis of branched chain hydrocarbons whichcomprises reacting an isoparaflin with an olefin under alkylatingconditions in the presence of a catalyst consisting essentially of borontrifluoride' and an alkali metal mono hydrofluoride.

16. A process tor the synthesis of branched chain hydrocarbons whichcomprises passing isoparamnic hydrocarbons, oleflnic hydrocarbons, andboron trifluoride throu'gh'ari alkylation zone containing therein afixed bed of a solid contact material comprising an alkali metal acidfluoride, separating boron trifluoride i'rom the hydrocarbon reactionproducts, recycling said boron trifluoride to the alkylation zone andiractionating said hydrocarbon reaction products to recover desiredalkylation products. i

17. The process or claim 16 wherein said solid contact material consistsessentially or potassium acid fluoride as its active ingredient.

18. The process of claim 16 wherein said solid contact material consistsessentially 01' sodium acid fluoride as its active ingredient.

19. An alkylation process which comprises reacting a branched chainparaflln with an olefin in the presence of boron trifluoride and analkali metal acid fluoride. A

- CARL .B. LINN.

VLADIMIR. N. IPATIEFF.

